CopyOutputResult must have a working release callback when received over mojo

cc/ipc/copy_output_result_struct_traits.cc

 // Copyright 2017 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/ipc/copy_output_result_struct_traits.h"
 
+#include "mojo/public/cpp/bindings/strong_binding.h"
+
+namespace {
+
+class TextureMailboxReleaserImpl : public cc::mojom::TextureMailboxReleaser {

[Fady Samuel, 2017/02/11 16:36:57]

nit: Please add a comment about where this code runs, and what its lifetime
is...in the display compositor, and lives as long as a client holds on to the
MessagePipe (StrongBinding),

+ public:
+  TextureMailboxReleaserImpl(
+      std::unique_ptr<cc::SingleReleaseCallback> release_callback)
+      : release_callback_(std::move(release_callback)) {}
+
+  // mojom::TextureMailboxReleaser implementation:
+  void Release(const gpu::SyncToken& sync_token, bool is_lost) override {
+    release_callback_->Run(sync_token, is_lost);
+  }
+
+ private:
+  std::unique_ptr<cc::SingleReleaseCallback> release_callback_;
+};
+
+void Release(cc::mojom::TextureMailboxReleaserPtr ptr,

[Fady Samuel, 2017/02/11 16:36:57]

nit: Please a comment about where this is used: in the client and bound to a
SingleReleaseCallback.

+             const gpu::SyncToken& sync_token,
+             bool is_lost) {
+  ptr->Release(sync_token, is_lost);
+}
+
+}  // namespace
+
 namespace mojo {
 
 // static
+const SkBitmap& StructTraits<cc::mojom::CopyOutputResultDataView,
+                             std::unique_ptr<cc::CopyOutputResult>>::
+    bitmap(const std::unique_ptr<cc::CopyOutputResult>& result) {
+  static SkBitmap* null_bitmap = new SkBitmap();
+  if (!result->bitmap_)
+    return *null_bitmap;
+  return *result->bitmap_;
+}
+
+// static
+cc::mojom::TextureMailboxReleaserPtr
+StructTraits<cc::mojom::CopyOutputResultDataView,
+             std::unique_ptr<cc::CopyOutputResult>>::
+    releaser(const std::unique_ptr<cc::CopyOutputResult>& result) {
+  if (!result->release_callback_)
+    return {};
+  cc::mojom::TextureMailboxReleaserPtr releaser;
+  auto impl = base::MakeUnique<TextureMailboxReleaserImpl>(
+      std::move(result->release_callback_));
+  MakeStrongBinding(std::move(impl), MakeRequest(&releaser));
+  return releaser;
+}
+
+// static
 bool StructTraits<cc::mojom::CopyOutputResultDataView,
                   std::unique_ptr<cc::CopyOutputResult>>::
     Read(cc::mojom::CopyOutputResultDataView data,
          std::unique_ptr<cc::CopyOutputResult>* out_p) {
   auto result = cc::CopyOutputResult::CreateEmptyResult();
 
   if (!data.ReadSize(&result->size_))
     return false;
 
   result->bitmap_ = base::MakeUnique<SkBitmap>();
   if (!data.ReadBitmap(result->bitmap_.get()))
     return false;
 
   if (!data.ReadTextureMailbox(&result->texture_mailbox_))
     return false;
 
+  auto releaser = data.TakeReleaser<cc::mojom::TextureMailboxReleaserPtr>();
+  if (releaser) {
+    result->release_callback_ = cc::SingleReleaseCallback::Create(
+        base::Bind(Release, base::Passed(&releaser)));
+  }
+
   *out_p = std::move(result);
 
   return true;
 }
 
-// static
-const SkBitmap& StructTraits<cc::mojom::CopyOutputResultDataView,
-                             std::unique_ptr<cc::CopyOutputResult>>::
-    bitmap(const std::unique_ptr<cc::CopyOutputResult>& result) {
-  static SkBitmap* null_bitmap = new SkBitmap();
-  if (!result->bitmap_)
-    return *null_bitmap;
-  return *result->bitmap_;
-}
-
 }  // namespace mojo